


Beneath the Surface

by Th3spian



Category: Lucky Star (Anime & Manga)
Genre: Angst, Emotional Hurt/Comfort, F/F, Loss of Virginity, Secret Relationship, Sister/Sister Incest, Twincest
Language: English
Status: In-Progress
Published: 2020-11-12
Updated: 2020-12-31
Packaged: 2021-03-09 05:35:35
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,696
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27499528
Author URL: https://archiveofourown.org/users/Th3spian/pseuds/Th3spian
Summary: After watching Kagami's relationship with Konata fall apart, Tsukasa decides to come clean about her own feelings. The twins are forced to reevaluate what they mean to each other, all while trying to keep their forbidden romance a secret.
Relationships: Hiiragi Kagami/Hiiragi Tsukasa
Kudos: 5





	1. Indiscretion

**Author's Note:**

> All characters are eighteen years of age or older.
> 
> This is very loosely based on a fic that I wrote a long time ago under another name. Kagami/Tsukasa is still one of my guilty pleasure ships, so I wanted to go back and give it another shot.

It had been five months since Konata and Kagami confessed their feelings for each other and began dating. They had been friends for years, and once there was nothing holding them back, they dove headfirst into romance. Tsukasa had tried her hardest to be supportive, but she couldn’t shake the feeling that something was wrong.

The first few weeks were a whirlwind of passion. Unlike before, when Tsukasa would get to eat lunch with them every day at school, they insisted on going off and spending that time by themselves. Anytime Konata would come over to “study,” there was a certain awkwardness that made Tsukasa feel like a third wheel. On one occasion she peeked into Kagami’s room to find her flat on her back, arms wrapped around her new girlfriend. It was like they never wanted to be away from each other.

As the initial excitement faded, so did Tsukasa’s patience. Whether she wanted it or not, she had a front-row seat to every quarrel the couple had. She had given up counting the times she sat in her room and overheard Kagami argue with Konata on the phone, wishing the walls were just a little bit thicker. It was obvious to her that just because they got along as friends didn’t necessarily mean they would be good as lovers. She knew Kagami was unhappy and felt powerless to save her.

What hurt the most, though, was the jealousy. As much as she tried to deny it, she held a forbidden love deep within herself: a love for her own flesh and blood. She had yearned for Kagami for as long as she could remember and seeing her with someone else just made it worse. She couldn’t even watch Kagami hold Konata’s hand without feeling like her heart was splitting in half. Over and over, she would fantasize about trading places with Konata and doing those same romantic things with her sister, only to feel sick to her stomach afterwards. Kagami was the first thing Tsukasa thought about when she woke up, and the last thing she thought about as she fell asleep.

Of course, that depended on her being able to fall asleep in the first place. On this particularly cold and dreary night, an episode of insomnia was keeping Tsukasa awake. She tried to cover her ears with a pillow, but she could still hear what was happening in the next room over. Judging by the half of the conversation Tsukasa could hear, things were going from bad to worse.

“I can’t deal with this shit anymore,” Kagami said, sounding defeated. “We’re through.” Moments later, Tsukasa could hear a door opening, followed by footsteps and the occasional sob. She hid under her blanket in case Kagami came in, but nothing happened. Instead, the heart-rending sound of her cries grew louder. Tsukasa couldn’t ignore it any longer; she needed to do something.

Tsukasa slowly opened her bedroom door and tiptoed down the hall in search of Kagami. “Sis, are you okay?” she called out, trying not to wake the rest of the family.

Kagami poked her head out from the bathroom, her face red. “I’m fine. Just go back to bed.”

“I know that’s not true.” Tsukasa slowly approached, holding back her own tears. She was so used to being the one who needed someone to lean on that it felt strange to be on the other end. “I’ve been listening to you talk to Kona-chan all night. Please, just let me know what’s going on.” When they were at arm’s length from each other, she put her hands over her heart. “I love you.”

An awkward silence accompanied the gesture. The twins had seldom said that they loved each other, and never had those words carried as much weight as they did at that moment. That weight, though, seemed to be lost on Kagami. “Tsukasa, what are you doing?” she asked. “We’re sisters. Why are you acting like this is a big confession or something?”

“Because it is!” Tsukasa cried. “I’ve loved you since we were kids! As more than just sisters! Seeing things fall apart between you and Kona-chan is tearing me apart because I know you deserve better.” Her composure broke, and tears began streaming down her face. “I want to take her place.”

Kagami closed the distance and took Tsukasa’s hand. “Hey, if we’re gonna talk about this stuff, let’s not do it in the middle of the hallway.” They retreated to Kagami’s room, where they could have more privacy. As soon as the door closed behind them, they threw their arms around each other. Only then did Tsukasa realize how badly this could go for her. If Kagami didn’t feel the same way, their relationship was likely damaged for good. The shame and regret hit her like a ton of bricks, and she fell to her knees, crying even harder than earlier.

“I’m so sorry,” Tsukasa said between heaves while covering her face.

Kagami knelt and hugged Tsukasa again. “It’s okay,” she whispered. “I’ve got you.” Tsukasa may have intended to comfort her sister, but as it turned out, they both needed to be comforted. They sat on the floor together and continued to hold each other, not saying anything for a little while.

Once she had calmed down, Tsukasa took a deep breath. “So, does this mean you accept my confession?” she asked.

“I…I don’t know yet,” Kagami answered. “I kind of always suspected you felt this way. We’ve been inseparable since the day we were born. You always clung more tightly to me than anyone else. And I’ll be honest: I’ve had days when I wished we weren’t siblings, and that _you_ could be my girlfriend instead of Konata. But the fact remains that we are siblings. If we go down this road, a lot of people won’t approve, and we’d probably never hear the end of it if Mom and Dad found out. You realize that, right?”

Tsukasa felt butterflies in her stomach. She didn’t disagree with what Kagami was saying, but it hurt all the same. “I do, but…”

“Sorry, I know this isn’t a good time to be lecturing you. I just have a lot on my mind. Do you want to move to the bed?”

The two slowly got comfortable between the sheets. Tsukasa scanned Kagami’s face, admiring every part of it. Her deep blue eyes, tiny nose, rosy cheeks, and especially her pink lips were all beautiful. Tsukasa recalled a dream she had about Kagami when they were ten years old. She dreamt that they were walking hand in hand through a garden. They came to a stone bench, and while sitting on it, Kagami gave her a kiss. The memory of that dream came back periodically over the years, and every time, she hoped against hope that it would come true one day.

“What’re you thinking about?” Kagami asked.

Tsukasa tried to come up with a lie, but she had already admitted so much that it only made sense to be honest. “How much I’d like to kiss you.”

Instead of replying, Kagami brushed her hair back and moved her face close enough that their noses touched. It was Tsukasa’s last chance to change her mind. She knew that what she was about to do was taboo, but she could worry about that later. She closed her eyes and gently cupped Kagami’s cheeks before bringing her lips the rest of the way. It was every bit as enthralling as it had been in her dream. She felt herself drifting off into a state of utter bliss as she sank further and further into Kagami’s arms.

After hearing the soft popping sound of lips separating, Tsukasa opened her eyes, still in disbelief over what had just happened. Kagami stared back at her with a face that looked like it was full of guilt. “I just…took my little sister’s first kiss,” she thought aloud. “That’s supposed to be for someone special, and yet I…”

“Sis, you _are_ special. I always hoped you would be my first. In more ways than one, actually.”

Kagami blushed from the uncharacteristic boldness of what she just heard. “In that case, do you want to keep going?”

Tsukasa pulled her into another kiss. There was so much tension between them that it was like releasing a slingshot. Any sense of restraint was gone the moment their tongues met. Their hands began to explore each other’s bodies as their clothes gradually came off. They were so overtaken by lust that they accidentally tumbled out of bed and onto the floor. The next thing Tsukasa knew, they were both naked, and Kagami had her pinned down. She had never been so turned on in her life.

“Are you sure, Tsukasa?”

“Yes. I’m all yours, Sis.”


	2. Aftermath

The first thing Tsukasa felt in the morning was a hand gently stroking the top of her head. Though she was awake, she kept her eyes closed, hoping this lovely feeling would continue. The warm bedsheets that surrounded her body felt heavier than usual. It was all so peaceful that it didn’t take long for her to doze off again. Besides, today was Sunday, a day she normally spent doing little more than sleeping.

Getting to wake up next to her beloved sister was a rare treat. Being awoken by a soft kiss on the lips from her was even rarer. It was slow and restrained, conveying an innocent, sincere affection. It was nothing like the deep, occasionally sloppy kisses they had shared the night before while embracing each other. Tsukasa’s consciousness gradually came back to her as she returned the kiss.

“Good morning, sleepyhead. It’s time to get up.”

Tsukasa’s eyes fluttered open. She saw Kagami, whose pajama top was still unbuttoned, staring back at her. “Good morning, Sis,” she said softly. “How did you sleep?”

“Well, since _someone I could mention_ kept me up all night, I could only get so much rest,” Kagami teased. “You were great, by the way.”

Despite the pillow talk, they were ignoring an undeniable fact: their relationship was never going to be the same. Anytime Tsukasa looked at Kagami from now on, she would be reminded of the fact that she lost her virginity to her. Even if they tried going back to just being sisters, they would still have to take this secret to their graves. Then again, it wasn’t like this was a surprise. They knew what the consequences would be if they gave into their desires, and they did it anyway. The worst part was Tsukasa wasn’t even sure whether she regretted it.

“To tell you the truth,” Kagami continued, “it never even occurred to me that you were gay.”

“I never really thought about it,” Tsukasa said in response. If she had to put a label on her sexuality, she would probably say she was bisexual. Although she had on occasion found herself attracted to one boy or another, that attraction paled in comparison to what she felt for Kagami. “All I know is that I’m in love with you. Can’t that be enough?”

“Of course.” Kagami got back under the covers and held Tsukasa’s hand. “I think we’re both still processing what happened last night. Would you like to go out today, just so we can have some quality time together?”

Tsukasa nodded. “That would be wonderful, but let’s get something to eat first.”

The twins got dressed and headed to the kitchen for breakfast. Tsukasa suddenly thought back to all the noise they had made in the middle of the night. As it turned out, she could moan quite loudly when touched in just the right places, and Kagami wasn’t exactly a silent lover either. She had no idea if the rest of the family had heard them or simply slept through it. Every time someone greeted them, she wondered if they would say something about it. The dread was enough to make her feel nauseous, but she did her best not to show it as she ate.

“Is everything alright, sweetie?” her mom asked.

“I just, um, didn’t get much sleep last night,” Tsukasa answered, trying to play it cool.

“It didn’t have anything to do with that loud thumping sound, did it? Was that you?”

Tsukasa’s heart sank. She knew exactly what her mom was talking about: the sound she and Kagami made when they fell off the bed. It couldn’t have been anything else. If she told the truth, the next question would obviously be why they were in the same bed in the first place, and then she would have no way out.

“She had a bad dream and wanted to sleep with me,” Kagami interrupted. “It was hard to see where the edge of the bed was in the dark, so I fell.” They had slept together before, so her lie wasn’t hard to believe.

“Oh. Well, try to be more careful next time.” The conversation moved onto something else, and a bullet was dodged.

That afternoon, Tsukasa and Kagami headed out for the day. For all anyone else knew, they were just two sisters walking down the street together. No one would have suspected the sparks that were flying whenever they glanced at each other. At least, that’s what Tsukasa kept telling herself. She wanted to be more openly affectionate, but she knew it would only cause problems, so she had to keep her hands at her sides.

Their destination was a popular date location in the area: a small family-owned café. As they expected, there were plenty of couples happily talking to each other inside, allowing the twins to hide in plain sight. Tsukasa ordered a mocha, while Kagami got a dark roast. Once they got their drinks, they found an empty booth and sat down.

“I’m sorry things didn’t work out with you and Kona-chan,” Tsukasa said. “Do you want to talk about it?”

Kagami absentmindedly swirled the spoon around her cup of coffee. “Dating makes everything so complicated. You think you know someone, but once you open your heart to them, it’s like they’re a different person. You see parts of them that you never would have imagined before. It was easy at first because we couldn’t keep our hands off each other, but when we started thinking about our future together, it all fell apart. That’s why we’ve been bickering so much.”

“Do you think you can at least go back to being friends?”

“I hope so, but right now I just need some time to grieve.” Kagami took a sip of her drink. “I’m really glad you were the one who reached out, Tsukasa. No one gets me the way you do. Maybe it’s not so bad that things went the way they did last night.”

Tsukasa checked to make sure no one was watching them and then looked back at Kagami. “What does that make us, then?” she asked quietly. “We’ve probably gone far enough now to be lovers.”

Kagami sighed. “I still don’t know. I mean, for one thing, you’re still my sister. That will never change, but we’re clearly something more now. I just don’t know what to call it. Maybe we should try to take things one step at a time until we figure it out.”

_I doubt she’d be so unsure if we weren’t related,_ Tsukasa thought. She had hoped that going on a romantic date with Kagami would make her more open about her feelings, but instead it only made things more awkward. Again, she wondered if it was a mistake to give her first time to someone who could never openly love her back, but it didn’t stop the aching in her heart. If only Tsukasa had been just another girl, maybe she could try to give Kagami the happiness she couldn’t find with Konata. Would it have been better if she had simply minded her own business and held her tongue instead of revealing her terrible secret? She looked around wistfully at the other couples in the café, her mood becoming as bitter as the drink in front of her.


End file.
